A battery pack has been proposed as a clean, efficient and environmentally responsible power source for electric vehicles and various other applications. The battery pack typically includes numerous components and devices such as a plurality of individual battery cells, a plurality of spaced apart battery holders, cooling conduits, and control modules, for example. Two types of battery cells are a nickel-metal hydride (NiMH) cell and a lithium-ion battery cell. Both the NiMH and the lithium-ion battery cells are rechargeable and can be formed into a wide variety of shapes and sizes so as to efficiently fill available space in electric vehicles.
Both the NiMH and the Lithium-ion battery cells are known to generate heat during a charge and discharge cycle of operation. Overheating of the battery cells or an exposure thereof to high-temperature environments, may undesirably affect the operation of the battery assembly. Accordingly, cooling systems are typically employed with the battery cells in the battery pack. Prior art cooling systems, however, cause a significant temperature variation among the individual battery cells and a substantial pressure variation in fluid channels formed between the battery cells. Particularly, a pressure drop of the fluid channels at an inlet end of the battery pack is much lower than a pressure drop of the fluid channels at an outlet end of the battery pack. As a result, flow rates and surface convection coefficients of the fluid channels at the inlet end of the battery pack are less than flow rates and surface convection coefficients of the fluid channels at the outlet end of the battery pack.
Therefore, it is desirable to produce a battery pack including a cooling system, wherein temperature and pressure variations in the battery pack and a size thereof are minimized, and a capacity and a durability of the battery pack are maximized.